Abstract: 6201 alloy (Al-0.81Mg-0.79Si) with high Mg and Si contents was prepared by gravity casting.After solution treatment at 550 ℃×1 h, water quenching and three-pass rolling with 82.6% reduction at room temperature, the alloy was aged at 130 ℃ for different time (8-48 h).The effects of low temperature aging after cold rolled on the microstructure, hardness and conductivity of the alloy were investigated.The results show that, solution treatment results in alloy elements being dissolved in matrix and inducing lattice distortion.The hardness of the alloy obviously increases while the conductivity dramatically decreases.High density of dislocations and nonequilibrium vacancies produce during rolling, which induce the formation of nano precipitates.The hardness of the alloy increases sharply and the conductivity decreases slightly.Aging at 130 ℃ for 8 h accelerates the precipitation of high density of coherent nano precipitates to reach the peak aging, the hardness of the alloy is the largest and the conductivity is improved significantly.24 h and longer aging results in over-aging and precipitation saturation as the precipitates are segregated and incoherent precipitates form, the hardness of the alloy decreases significantly until it remains constant.With the prolongation of the time, the defects such as dislocation and vacancy are annihilated continuously, and the conductivity of the alloy continues to increase.